On Thu, Mar 05, 2009 at 08:16:14PM -0500, David Shaw wrote:
> If a filesystem being written to via NFS returns a short write count
> (as opposed to an error) to nfsd, nfsd treats that as a success for
> the entire write, rather than the short count that actually succeeded.
>
> For example, given a 8192 byte write, if the underlying filesystem
> only writes 4096 bytes, nfsd will ack back to the nfs client that all
> 8192 bytes were written. The nfs client does have retry logic for
> short writes, but this is never called as the client is told the
> complete write succeeded.
>
> There are probably other ways it could happen, but in my case it
> happened with a fuse (filesystem in userspace) filesystem which can
> rather easily have a partial write.
Got it.
>
> Here is a patch to properly return the short write count to the
> client.
Applied for-2.6.30 with one minor style fix, noted below.
Looks good, thanks for your persistance.--b.
>
> Signed-off-by: David Shaw <dshaw@xxxxxxxxxxxxxxx>
> ---
>
> fs/nfsd/nfs3proc.c | 5 +++--
> fs/nfsd/nfs4proc.c | 7 +++++--
> fs/nfsd/nfsproc.c | 3 ++-
> fs/nfsd/vfs.c | 12 +++++++-----
> include/linux/nfsd/nfsd.h | 2 +-
> 5 files changed, 18 insertions(+), 11 deletions(-)
>
> diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
> index 9dbd2eb..9f262b3 100644
> --- a/fs/nfsd/nfs3proc.c
> +++ b/fs/nfsd/nfs3proc.c
> @@ -202,6 +202,7 @@ nfsd3_proc_write(struct svc_rqst *rqstp, struct nfsd3_writeargs *argp,
> struct nfsd3_writeres *resp)
> {
> __be32 nfserr;
> + unsigned long cnt = argp->len;
>
> dprintk("nfsd: WRITE(3) %s %d bytes at %ld%s\n",
> SVCFH_fmt(&argp->fh),
> @@ -214,9 +215,9 @@ nfsd3_proc_write(struct svc_rqst *rqstp, struct nfsd3_writeargs *argp,
> nfserr = nfsd_write(rqstp, &resp->fh, NULL,
> argp->offset,
> rqstp->rq_vec, argp->vlen,
> - argp->len,
> + &cnt,
> &resp->committed);
> - resp->count = argp->count;
> + resp->count = cnt;
> RETURN_STATUS(nfserr);
> }
>
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 9fa60a3..8ed1b93 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -685,6 +685,7 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> struct file *filp = NULL;
> u32 *p;
> __be32 status = nfs_ok;
> + unsigned long cnt;
>
> /* no need to check permission - this will be done in nfsd_write() */
>
> @@ -703,7 +704,7 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> return status;
> }
>
> - write->wr_bytes_written = write->wr_buflen;
> + cnt = write->wr_buflen;
> write->wr_how_written = write->wr_stable_how;
> p = (u32 *)write->wr_verifier.data;
> *p++ = nfssvc_boot.tv_sec;
> @@ -711,10 +712,12 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>
> status = nfsd_write(rqstp, &cstate->current_fh, filp,
> write->wr_offset, rqstp->rq_vec, write->wr_vlen,
> - write->wr_buflen, &write->wr_how_written);
> + &cnt, &write->wr_how_written);
> if (filp)
> fput(filp);
>
> + write->wr_bytes_written = cnt;
> +
> if (status == nfserr_symlink)
> status = nfserr_inval;
> return status;
> diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
> index 6f7f263..e298e26 100644
> --- a/fs/nfsd/nfsproc.c
> +++ b/fs/nfsd/nfsproc.c
> @@ -180,6 +180,7 @@ nfsd_proc_write(struct svc_rqst *rqstp, struct nfsd_writeargs *argp,
> {
> __be32 nfserr;
> int stable = 1;
> + unsigned long cnt = argp->len;
>
> dprintk("nfsd: WRITE %s %d bytes at %d\n",
> SVCFH_fmt(&argp->fh),
> @@ -188,7 +189,7 @@ nfsd_proc_write(struct svc_rqst *rqstp, struct nfsd_writeargs *argp,
> nfserr = nfsd_write(rqstp, fh_copy(&resp->fh, &argp->fh), NULL,
> argp->offset,
> rqstp->rq_vec, argp->vlen,
> - argp->len,
> + &cnt,
> &stable);
> return nfsd_return_attrs(nfserr, resp);
> }
> diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> index 6e50aaa..d3c8429 100644
> --- a/fs/nfsd/vfs.c
> +++ b/fs/nfsd/vfs.c
> @@ -960,7 +960,7 @@ static void kill_suid(struct dentry *dentry)
> static __be32
> nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
> loff_t offset, struct kvec *vec, int vlen,
> - unsigned long cnt, int *stablep)
> + unsigned long *cnt, int *stablep)
> {
> struct svc_export *exp;
> struct dentry *dentry;
> @@ -974,7 +974,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
> err = nfserr_perm;
>
> if ((fhp->fh_export->ex_flags & NFSEXP_MSNFS) &&
> - (!lock_may_write(file->f_path.dentry->d_inode, offset, cnt)))
> + (!lock_may_write(file->f_path.dentry->d_inode, offset, *cnt)))
> goto out;
> #endif
>
> @@ -1006,7 +1006,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
> host_err = vfs_writev(file, (struct iovec __user *)vec, vlen, &offset);
> set_fs(oldfs);
> if (host_err >= 0) {
> - nfsdstats.io_write += cnt;
> + nfsdstats.io_write += host_err;
> fsnotify_modify(file->f_path.dentry);
> }
>
> @@ -1051,8 +1051,10 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
> }
>
> dprintk("nfsd: write complete host_err=%d\n", host_err);
> - if (host_err >= 0)
> + if (host_err >= 0) {
> err = 0;
> + *cnt = host_err;
> + }
> else
That should be } else
--b.
> err = nfserrno(host_err);
> out:
> @@ -1095,7 +1097,7 @@ out:
> */
> __be32
> nfsd_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
> - loff_t offset, struct kvec *vec, int vlen, unsigned long cnt,
> + loff_t offset, struct kvec *vec, int vlen, unsigned long *cnt,
> int *stablep)
> {
> __be32 err = 0;
> diff --git a/include/linux/nfsd/nfsd.h b/include/linux/nfsd/nfsd.h
> index e19f459..eefa241 100644
> --- a/include/linux/nfsd/nfsd.h
> +++ b/include/linux/nfsd/nfsd.h
> @@ -105,7 +105,7 @@ void nfsd_close(struct file *);
> __be32 nfsd_read(struct svc_rqst *, struct svc_fh *, struct file *,
> loff_t, struct kvec *, int, unsigned long *);
> __be32 nfsd_write(struct svc_rqst *, struct svc_fh *,struct file *,
> - loff_t, struct kvec *,int, unsigned long, int *);
> + loff_t, struct kvec *,int, unsigned long *, int *);
> __be32 nfsd_readlink(struct svc_rqst *, struct svc_fh *,
> char *, int *);
> __be32 nfsd_symlink(struct svc_rqst *, struct svc_fh *,
> --
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